Anchoring devices of the above type are known and constructed so that one end thereof is secured in the ground, for example, in a hole drilled into a rock and then secured therein by cementing. The portion of the anchor extending out of the ground is provided with the eyelete that in turn is connected to the protection netting made, for example, of steel wires or cables or the like. Such netting provides protection against falling rocks or avalanches or the like.
Conventional anchors of this type are exposed to long term corrosion which poses a substantial problem with regard to the strength of such anchoring devices, especially since such anchoring devices are expected to remain functional for many years, even decades under all weather conditions.
Conventionally, corrosion protection is provided by using galvanized steel wires for forming the steel cables that are part of the anchoring device. However, galvanized wires have not been satisfactory, because the movements to which these anchors are exposed during service cause the removal or damage of the galvanized surface. Such movements occur when the effective forces change directions, for example, under the influence of a snow load or when temperature variations cause a lengthening or shrinking in the netting. As a result, the anchor, especially its eyelet is also exposed to motions which adversely affect the anchor's ability to resist corrosion. This adverse influence is especially effective on that portion of the anchor that extends out of the ground and is exposed to the effects of alternating loads. Additionally, the area of the steel cable close to the ground is particularly exposed to corrosion advancing influences, such as oxygen in the air close to the ground, moisture and water in the ground, heat influences and acidic soil or rock characteristics. These influences eventually cause corrosion damage of the individual wires in the cable, thereby reducing their strength individually and of the cable. Such corrosion damage will accumulate over time to such an extent that these anchors are no longer capable of performing their intended purpose of holding the protection systems.